Here are five pitfalls that you should avoid in order to maximize your 401(k) nest egg.

Not exploring investment options

401(k) participants spend more time researching options for a new car or vacations than researching their 401(k) investment choices. According to a survey, while 55% of people spend more than five hours conducting research before buying a car, only 11% of those same people spend that much time before making an investment choice for their 401(k).

Part of the problem may be that people don't understand their 401(k) investment options. About half of those people surveyed find 401(k) investment materials more confusing than health care benefits materials. Instead of doing it on your own, consider that over half of retirement plans have individual investment advice offered on a one-on-one basis.

Borrowing from a 401(k)

An average of 13,000 people take a loan each month out of their 401(k)s for a median loan of about $4,600. Borrowing from your 401(k) is bad idea for several reasons:

Taking cashouts when switching jobs

When you leave your job, you typically have to choose between taking a cash-out or rolling your 401(k) into a qualifying individual retirement account (IRA). While the first option is taxable, the second one is not.

Taking cashouts when switching jobs is a dumb mistake for three reasons:

If you're under age 59 ½, you're liable for both income tax and a 10% early distribution tax;

You may not get as much as you think. Some 401(k) plans have a vesting period for employer contributions. Pay special attention if your plan has a cliff-vesting schedule for employer contributions, which means that you only become eligible for employer contributions after a specified date.

There is a limit to how much you can contribute to your 401(k) every year. In 2015, the maximum contribution limit to a 401(k) is $18,000. This means that once you cashout monies, they may never make it back to your nest egg, without forfeiting part of your future contributions.

If you already took a cashout, still have the money, and are within 60 days from the cashout date, you still have time to roll the money over to an IRA. Don't waste time and avoid taxes!

Not taking advantage of the retirement saver's credit

This is one time that you want to call up the tax man.

Even though you may feel that you're not making much money, you're still very diligently contributing to your 401(k) or other qualifying retirement plan. Uncle Sam would like to reward your hard work by providing you a tax break through the retirement saver's credit.

In 2015, the retirement saver's credit provides a tax credit based on your adjusted gross income (AGI). For example, a married couple filing jointly receives a tax credit that is:

50% of 401(k) contributions when AGI is under $36,500;

20% of 401(k) contributions when AGI is between $36,501 and $39,500; and

10% of 401(k) contributions when AGI is between $36,501 and $61,000.

Married couples filing jointly can receive up to $4,000 ($2,000 for all other filers) in retirement saver's credit. This is one of the many reasons why it is important to start saving for retirement as early as possible. Depending on your AGI, you can take advantage of tax breaks such as this. Plus, you can always defer taxes until retirement, when you're more likely to be in a lower tax bracket.

Self-employed: not having a solo 401(k)

Independent contractors, freelancers, and small business owners may think that they're not eligible to open a 401(k). They'd be wrong. They can open a solo 401(k), also known as an one-participant k or uni-k.

Solo 401(k) plans enable the self-employed to save up larger sums for retirement. If you're a sole proprietor and have no employees, you can contribute to your solo 401(k) as employer and employee.

For example, let's imagine that you have an S-corporation and earned $40,000 in 2014. You can contribute the maximum $17,500 allowed to your solo 401(k), and your S-corporation can contribute an additional 25% to the plan (an additional $10,000). The total contributions to your nest egg for 2014 would be $27,500.

This example shows how a solo 401(k) is a powerful way to catch up in the race for retirement. The IRS allows total contributions to a solo 401(k), not counting catch-up contributions for those age 50 and over, of up to $52,000 for 2014, and $53,000 for 2015. If your spouse earns income from your business, then you can double those contribution limits.